The error appears because your variables (at least some of them) contain colons (:) and you use a colon as the delimiter for the s/…/…/ command. Actually for the s:…:…: command in your case.
When you have
var="ex:ample"
and then try to issue
sed -e "s:${var}:sample:g" some_file
then the shell interpolates the variable before handing it over to sed, and sed is called like so:
sed -e "s:ex:ample:sample:g" some_file
and the s:…:…: is now broken. It looks like you are telling sed to replace ex with ample and apply the options s, a, m, p, l, and e.
To avoid this, use a different delimiter which you are sure of it doesn't appear in your text. Popular delimiters are + and # but you can choose any character. The delimiter is in fact the first character after the s, so
sed -e "s#…#…#" some_file
sed -e "s+…+…+" some_file
sed -e "s'…'…'" some_file
will all do.